1. Field of the Invention
This invention relates to a process for treating the backside of a semiconductor wafer. More particularly, the invention comprises a process for treating the backside of a semiconductor wafer in a manner which will result in the absence of materials on the backside of the wafer which would otherwise interfere with subsequent processing of the wafer.
2. Description of the Related Art
In the formation of integrated circuit structure on a semiconductor wafer such as a silicon wafer, a number of different materials are deposited, patterned, and etched during the construction of the integrated circuits on the wafer.
During each of these steps, it is of utmost importance that no foreign materials, including dust or dirt particles, be in contact with the surface of the wafer, since precise alignment of each patterned layer is essential and the presence of any foreign materials could interfere with the deposition of a layer by causing imperfections in the layer, as well as interfere with the photolithography or etching steps.
In particular, it has been found that if a coating material such as tungsten is deposited on the integrated circuit structure, deposition of a layer of tungsten on the backside of the silicon wafer may occur as well. Unfortunately, this layer of tungsten which deposits on the backside of a silicon wafer adheres rather poorly, resulting in the flaking off of portions of the tungsten from the backside of the wafer. This, in turn, results in the deleterious formation of loose particles which interfere with the remainder of the processing as described above.
It has also been noted that the backside of a semiconductor wafer often comprises minor amounts of foreign materials, including moisture, which must be removed prior to placing the wafer in a high vacuum environment to avoid long baking or outgassing times.
It would, therefore, be desirable to provide a process which would be capable of removing undesirable impurities from the backside of a semiconductor wafer and inhibit the deposit of undesirable materials onto the backside of the wafer as well.